This invention relates to packet transmission systems operating with Bluetooth transmission protocols and more particularly to Bluetooth-enabled devices employed in carrying out multi-channel transmission in such systems.
Bluetooth-enabled devices utilize spread-spectrum frequency hopping techniques to exchange packet data with other Bluetooth-enabled devices in a piconet after activation of radio connections (or channels) between radio modules associated with the respective devices. Pursuant to Bluetooth protocols, each “master” device that initiates such connection thereafter communicates with the associated “slave” devices through the transmission of packets of a unique channel hopping pattern in successive time slots. The frequency hops of each pattern in the successive time slots are distributed in a quasi-random manner within the Industrial-Scientific-Medical (ISM) band typically used for Bluetooth transmission.
Plural channels may be activated for simultaneous transmission to separate piconets by separate masters. The masters utilize radio modules operating with different channel hopping patterns within the Bluetooth band. One concern with such arrangements is that the quasi-random distribution of frequency hops of each channel hopping pattern on the activated channels can result in certain time slots wherein the separate channels exhibit identical frequency hops. If such coincidence occurs in channels that are within Bluetooth range of each other (typically 10–100 meters), such frequency “collisions” can lead to loss of transmitted information in the affected time slots.
In order to effectively control such problem it is first necessary to predict where and when such collisions will take place. Up to now, no reliable means for predicting the occurrence of such collisions have been available.